Depression of mitochondrial respiration during daily torpor of the Djungarian hamster,Phodopus sungorus,is specific for liver and correlates with body temperature

Small mammals actively decrease metabolism during daily torpor and hibernation to save energy. Increasing evidence suggests depression of mitochondrial respiration during daily torpor of the Djungarian hamster but tissue-specificity and relation to torpor depth is unknown. We first confirmed a previous study by Brown and colleagues reporting on the depressed substrate oxidation in isolated liver mitochondria of the Djungarian hamster (Phodopus sungorus) during daily torpor. Next, we show that mitochondrial respiration is not depressed in kidneys, skeletal muscle and heart. In liver mitochondria, we found that state 3 and state 4 respirations correlate with body temperature, suggesting inhibition related to torpor depth and to metabolic rate. We conclude that molecular events leading to depression of mitochondrial respiration during daily torpor are specific to liver and linked to a decrease in body temperature. Different tissue-specificity of mitochondrial depression may assist to compare and identify the molecular nature of mitochondrial alterations during torpor.     

DEVELOPMENT OF A BIMODAL HEART RATE PATTERN IN UNDISTURBED FETAL HARBOR SEALS

Fetal and maternal heart rates were studied in unrestrained, pregnant harbor seals during the last third of gestation. Heart rates were recorded while the mothers were resting on land or performing trained simulated dives of up to 2.25 min. Data from resting mothers showed the development of a bimodal or two-speed fetal heart rate pattern during late gestation. The mean faster and slower fetal heart rates at term were 125 ± 3.7 and 79 ± 3.1 (mean + SEM) respectively. The amount of fetal bradycardia observed increased steadily towards term, and fetal heart rate changes were not correlated with changes in maternal heart rate or maternal respiration. The bimodal fetal heart rate was also seen during the simulated dives, and no decrease in either the faster or slower heart rate was found. Heart rates from resting, unrestrained harbor seal pups were also studied. The pups displayed a bimodal heart rate similar to the fetuses' with the slower rate occurring during breath-holds. The bradycardia in the pups was equivalent to the slower fetal heart rate. These findings suggest that the regulatory mechanism that determines the apneic bradycardia in young harbor seals during non-stressful conditions develops in the last quarter of gestation.     

Respiratory studies on two benthic copepods Acanthocyclops viridis and Eucyclops agilis at environmental temperatures

Summary The rate of oxygen consumption in all developmental stages of two benthic cyclopoid copepod species, Acanthocyclops viridis (Jurine) and Eucyclops agilis (Koch, Sars) was investigated at temperatures between 5° C–20° C, which are reflective of the environmental temperature range of the benthic zone in Esthwaite Water, Cumbria, from which the organisms were derived. The larger species, A. viridis was found to have a temperature insensitive metabolism, whereas E. agilis showed a marked temperature response in respiratory function. Gravid and non-gravid females had similar rates of respiration except at 15° C–20° C in E. agilis. Males exhibited much lower respiration rates than females, but higher weight specific respiration rates; these differences were largely attributable to size differentials between the sexes. Estimates of swimming activity were made and these were related to the patterns of respiratory function observed.     

Physiology of maternal separation in a bonnet macaque infant

A bonnet monkey infant (M. radiata) was monitored both physiologically and behaviorally during a separation experiment in which both its mother and other conspecifiecs were removed from its social group leaving the bonnet infant with three adult pigtailed females. The separated infant exhibited the characteristic slouched posture of depression and physiological changes including decreases in the heart rate and body temperature, increases in cardiac arrhythmias, and alterations in sleep patterns, as has been previously described in separated pigtailed infants. Persistent decreases in heart rate and body temperature were noted following reunion with the mother, possibly reflecting a disturbance in the mother-infant relationship secondary to the mother's having come into estrus during the period of separation. This study indicates that the physiological correlates of maternal separation previously described in pigtailed infants are not species specific.     

Embryonic duration and post-embryonic growth rates of the tropical freshwater shrimp Caridina nilotica (Decapoda:Atyidae) under laboratory and experimental field conditions

SUMMARY. Embryonic durations and post embryonic growth rates of Caridina nilotica were determined under laboratory conditions at constant temperatures near 18, 24 and 30°C. Embryonic durations and intermoult intervals were negative curvilinear functions of temperature. At a given temperature moulting frequency varied inversely with shrimp size and slight sexual differences were apparent. Moulting frequency of berried females was governed by the temperature-specific embryonic durations. Growth rates were determined from changes in carapace length (CL) of individual shrimps (laboratory) or batches of shrimps (field enclosures) over 1 month and these data were used to calculate temperature-specific life-long growth curves for males and females. Growth in body mass was estimated indirectly from the carapace length-mass relationship of C. nilotica. On average, males grew marginally faster than females during the first 2 months of life, but growth of males larger than CL= 4 mm was considerably depressed relative to that of females. Inflexions in growth rate, apparently related to the onset of sexual maturity, were apparent in both sexes. Under laboratory conditions, the growth rate of males increased with temperature, but temperature-related differences were not as marked in females. Notwithstanding the more rapid moulting rate at 30°C the growth rate of females was slightly slower at 30 than at 24°C as a result of marginally but significantly smaller per moult growth increments observed at 30°C in animals up to CL= 5.5 mm. Possible reasons for this depressed growth are discussed. Growth rates of animals in field enclosures in Lake Sibaya over 1 month in winter (20 ± 3°C) were generally comparable to those estimated for the 18°C laboratory experiments. Growth rates in enclosures containing tripled standing stocks were almost identical to those containing the naturally occurring biomass of animals, suggesting a non-limited environment at least during the time of the experiment.     

Respiration rates of two closely related species of carabids in Australia

Abstract The respiration rates of Notonomus gravis (Chaudoir) and N.philippi (Newman) (Coleoptera: Carabidae) were measured at temperatures between 10°C and 45°C. Mature males of both species had higher respiration rates than mature females. There was no difference between the rates of teneral male and female beetles at 30°C. The difference in respiration rates between the sexes is attributed to the maternal behaviour, and decreased surface activity, of mature females.     

SLC9B1 methylation predicts fetal intolerance of labor

Fetal intolerance of labor is a common indication for delivery by Caesarean section. Diagnosis is based on the presence of category III fetal heart rate tracing, which is an abnormal heart tracing associated with increased likelihood of fetal hypoxia and metabolic acidemia. This study analyzed data from 177 unique women who, during their prenatal visits (7-15 weeks and/or 24–32 weeks) to Atlanta area prenatal care clinics, consented to provide blood samples for DNA methylation (HumanMethylation450 BeadChip) and gene expression (Human HT-12 v4 Expression BeadChip) analyses. We focused on 57 women aged 18–36 (mean 25.4), who had DNA methylation data available from their second prenatal visit. DNA methylation patterns at CpG sites across the genome were interrogated for associations with fetal intolerance of labor. Four CpG sites (P value <8.9 × 10^?9, FDR <0.05) in gene SLC9B1, a Na⁺/H⁺ exchanger, were associated with fetal intolerance of labor. DNA methylation and gene expression were negatively associated when examined longitudinally during pregnancy using a linear mixed-effects model. Positive predictive values of methylation of these four sites ranged from 0.80 to 0.89, while negative predictive values ranged from 0.91 to 0.92. The four CpG sites were also associated with fetal intolerance of labor in an independent cohort (the Johns Hopkins Prospective PPD cohort). Therefore, fetal intolerance of labor could be accurately predicted from maternal blood samples obtained between 24–32 weeks gestation. Fetal intolerance of labor may be accurately predicted from maternal blood samples obtained between 24–32 weeks gestation by assessing DNA methylation patterns of SLC9B1. The identification of pregnant women at elevated risk for fetal intolerance of labor may allow for the development of targeted treatments or management plans.     

The Effect of Gestational State on Oxygen Consumption and Response to Hypoxia in the Sailfin Molly, Poecilia latipinna

Metabolic activity in livebearing fishes increases with embryonic development so that embryos prior to parturition may have a higher mass-specific oxygen requirement than maternal tissues, temporarily increasing the total routine oxygen requirement of the female. We examined whether females of the livebearing poeciliid Poecilia latipinna (sailfin molly) increase their routine metabolic oxygen consumption during development of their broods. We also quantified effects of gestation on time allocation to aquatic surface respiration (ASR) under hypoxic conditions. Mass-adjusted routine metabolic rate (RMR) of female mollies showed a significant increase during late gestation. The RMR of males did not differ from females that were in their early or mid stage of gestation, but was lower than females in late gestation. Gestating females spent approximately 27% more time conducting ASR than non-gestating females when exposed to chronic hypoxia (1mgl^–1), further supporting a brood-related increase in oxygen demand. Increased time allocation to ASR may directly affect maternal predation risk in low-oxygen conditions.     

Large seasonal changes in Q10 of soil respiration in a beech forest

We analyzed one year of continuous soil respiration measurements to assess variations in the temperature sensitivity of soil respiration at a Danish beech forest. A single temperature function derived from all measurements across the year (Q₁₀ = 4.2) was adequate for estimating the total annual soil respiration and its seasonal evolution. However, Q₁₀'s derived from weekly datasets ranged between three in summer (at a mean soil temperature of 14 °C) and 23 in winter (at 2 °C), indicating that the annual temperature function underestimated the synoptic variations in soil respiration during winter. These results highlight that empirical models should be parameterized at a time resolution similar to that required by the output of the model. If the objective of the model is to simulate the total annual soil respiration rate, annual parameterization suffices. If however, soil respiration needs to be simulated over time periods from days to weeks, as is the case when soil respiration is compared to total ecosystem respiration during synoptic weather patterns, more short‐term parameterization is required. Despite the higher wintertime Q₁₀'s, the absolute response of soil respiration to temperature was smaller in winter than in summer. This is mainly because in absolute numbers, the temperature sensitivity of soil respiration depends not only on Q₁₀, but also on the rate of soil respiration, which is highly reduced in winter. Nonetheless, the Q₁₀ of soil respiration in winter was larger than can be explained by the decreasing respiration rate only. Because the seasonal changes in Q₁₀ were negatively correlated with temperature and positively correlated with soil moisture, they could also be related to changing temperature and/or soil moisture conditions.     

Respiratory metabolism of Cyclops bicuspidatus (sensu stricta) (Claus) (Copepoda: Cyclopoida) from Esthwaite Water,Cumbria

Summary The respiration rate of all stages of Cyclops bicuspidatus (s. str.) (Claus), a benthic copepod, from Esthwaite Water in the English Lake District, was determined at a range of field temperatures, 4° C–12° C, using cartesian diver microrespirometry. The population of C. bicuspidatus in Esthwaite Water was found to be adapted to low temperatures, with an optimum rate of metabolism at 8° C. Weight varied with temperature, in general the largest weights occurred at the lower temperatures. Adult males had higher rates of respiration than adult females, which were on average twice the size of males. Gravid and non-gravid females had similar levels of metabolism. Regression coefficients (b), derived from regressions of log oxygen consumption against log dry weight were low, ranging between 0.25–0.51 according to temperature.     

Terrestrial apnoeas and the development of cardiac control in Australian fur seal (<Emphasis Type="Italic">Arctocephalus pusillus doriferus</Emphasis>) pups

The development of cardiac control in association with terrestrial respiration patterns was examined throughout the period of maternal dependence in Australian fur seal pups. Resting eupnoic heart rate and respiration rate were significantly correlated (r ² = 0.49) and both decreased with age (P < 0.05 in both cases). From an early age (1 month), pups displayed terrestrial apnoeas (18.1 ± 0.5 s) accompanied by substantial bradycardia (127 beats min⁻¹, a 13% decrease from eupnoic HR). Terrestrial apnoea duration increased significantly with age reaching a mean of 41 s just prior to weaning, slightly lower than the mean dive duration (52 s) previously recorded for pups of the same age. Correspondingly, mean apnoic heart rate decreased with age to 74 beats min⁻¹ just prior to weaning, representing a 25% decrease on eupnoic heart rate. Importantly, concomitant with the decrease in mean apnoic heart rate with age, an increase in the control of bradycardia was evident with the variability in instantaneous apnoic heart decreasing such that older pups were able to maintain a low steady heart rate for the duration of the apnoea. The changes seen in these parameters are similar to those reported during postnatal development in elephant seals (Mirounga spp.) and harbour seals (Phoca vitulina), and are considered indicative of the development of cardiac control. These findings suggest a common strategy for the development of bradycardia control in both otariid and phocid seals.     

毛白杨树干呼吸及其温度敏感性季节变化特征

树干呼吸(E_s)是森林生态系统碳循环过程的重要组成部分,深入理解树干呼吸过程对未来气候变暖的响应及反馈机制有助于更加精确地估算森林生态系统碳储量。为揭示毛白杨树干呼吸及其温度敏感性的昼夜变化和季节动态规律,利用Li-Cor6400便携式光合作用测定系统及其配套使用的土壤呼吸测量气室(LI-6400-09)对冀南平原区毛白杨的树干呼吸和树干温度实施为期1年的连续监测。结果表明:(1)在生长季,毛白杨树干呼吸与树干温度之间在晚上呈现正相关的关系(R~2=0.88);相反,两者在白天为负相关的关系(R~2=0.96)。(2)整个观测期内,毛白杨树干呼吸和树干温度均呈现"钟形"的变化曲线,树干呼吸与树干温度之间存在着较好的指数函数关系(R~2=0.93),且树干呼吸的温度敏感性系数(Q_(10))为2.62;不同季节毛白杨树干呼吸的Q_(10)存在差异,生长季的Q_(10)(1.95)明显低于非生长季(3.00),表明生长呼吸和维持呼吸对温度的响应也并不相同。(3)温度矫正后的毛白杨树干呼吸(R_(15))在昼夜和季节尺度上均存在明显的变异,即夜晚的R_(15)显著高于白天(P0.01),生长季的R_(15)明显高于非生长季(P0.05);树干可溶性糖含量与生长季的R_(15)存在较好的相关性(R~2=0.52),而非生长季的R_(15)却主要受到树干淀粉含量的影响。研究结果表明,在生长季,毛白杨树干呼吸的在日变化主要受到温度的影响,而在季节尺度上Q_(10)的变异则与树干呼吸中维持呼吸所占比例及树干中非结构性碳水化合物(可溶性糖和淀粉)的含量及类型紧密相关。     

Self-instructed relaxation: a therapeutic alternative

A self-instructed relaxation program was compared with therapist-instructed relaxation and waiting list controls. Self-report anxiety measures ( IPAT and STAI ) and a psychophysiological stress profile (frontal EMG, GSR, heart rate, finger temperature monitored under relaxation and stressor conditions) were utilized pre- and posttreatment to determine efficacy. Self-monitored heart rate, respiration rate, and finger temperature were used to monitor home practice sessions. Subjects reported increased ability to relax and control stress; however, frontal EMG measured under stressor conditions was the only dependent measure to confirm this perception. No between-group differences on any other dependent measures were observed. Reliable changes on all self-monitored home practice measures were observed, suggesting that this procedure is a useful gauge of home practice.     

氮添加和凋落物去除对黔中喀斯特地区柳杉人工林土壤呼吸的影响

凋落物是土壤呼吸的主要碳源,日益增加的大气氮沉降通过改变森林凋落物的输入与分解影响土壤呼吸。为揭示氮沉降及凋落物管理对森林土壤呼吸及其组分的影响,以贵州省国有扎佐林场15年生柳杉人工林为研究对象,设置4个氮添加处理:对照(CK,0 gN m^-2 a^-1)、低氮(LN,15 gN m^-2 a^-1)、中氮(MN,30 gN m^-2 a^-1)和高氮(HN,60 gN m^-2 a^-1),并在每种氮添加处理下设置去除凋落物和保留凋落物两种处理,于2021年3月-2022年2月利用LI-8100测定土壤呼吸速率,并分析氮添加及凋落物处理对土壤呼吸速率影响,确定影响土壤呼吸速率变化的主要因子。结果表明:氮添加和去除凋落物处理没有改变土壤呼吸速率的时间变化,土壤呼吸速率月均最大值出现在7月,月均最小值出现在2月。氮添加对土壤呼吸速率无显著影响(P > 0.05),除CK外,去除凋落物处理会显著降低土壤呼吸速率(P < 0.05)。凋落物对土壤总呼吸速率的贡献率为8.6%-28.5%,且LN处理下凋落物对土壤呼吸速率的贡献率最大。土壤呼吸速率与5 m土壤温度呈显著指数相关(P < 0.01),与5 cm土壤湿度呈显著负线性相关(P < 0.01)。土壤温度解释了土壤呼吸速率变异的58.5%-79.5%,土壤湿度解释了土壤呼吸速率变异的26.4%-39.5%,以土壤温度和湿度构建的双变量模型拟合效果均好于单因子模型,土壤温湿度共同解释土壤呼吸速率变异的59.1%-85.8%。结论表明在大气氮沉降增加的背景下,温度是影响土壤呼吸的主要因素,凋落物管理是调控土壤呼吸的关键过程。     

Annual variation in soil respiration and its components in a coppice oak forest in Central Italy

In order to investigate the annual variation of soil respiration and its components in relation to seasonal changes in soil temperature and soil moisture in a Mediterranean mixed oak forest ecosystem, we set up a series of experimental treatments in May 1999 where litter (no litter), roots (no roots, by trenching) or both were excluded from plots of 4 m². Subsequently, we measured soil respiration, soil temperature and soil moisture in each plot over a year after the forest was coppiced. The treatments did not significantly affect soil temperature or soil moisture measured over 0–10 cm depth. Soil respiration varied markedly during the year with high rates in spring and autumn and low rates in summer, coinciding with summer drought, and in winter, with the lowest temperatures. Very high respiration rates, however, were observed during the summer immediately after rainfall events. The mean annual rate of soil respiration was 2.9 µ mol m^?2 s^?1, ranging from 1.35 to 7.03 µmol m^?2 s^?1. Soil respiration was highly correlated with temperature during winter and during spring and autumn whenever volumetric soil water content was above 20%. Below this threshold value, there was no correlation between soil respiration and soil temperature, but soil moisture was a good predictor of soil respiration. A simple empirical model that predicted soil respiration during the year, using both soil temperature and soil moisture accounted for more than 91% of the observed annual variation in soil respiration. All the components of soil respiration followed a similar seasonal trend and were affected by summer drought. The Q₁₀ value for soil respiration was 2.32, which is in agreement with other studies in forest ecosystems. However, we found a Q₁₀ value for root respiration of 2.20, which is lower than recent values reported for forest sites. The fact that the seasonal variation in root growth with temperature in Mediterranean ecosystems differs from that in temperate regions may explain this difference. In temperate regions, increases in size of root populations during the growing season, coinciding with high temperatures, may yield higher apparent Q₁₀ values than in Mediterranean regions where root growth is suppressed by summer drought. The decomposition of organic matter and belowground litter were the major components of soil respiration, accounting for almost 55% of the total soil respiration flux. This proportion is higher than has been reported for mature boreal and temperate forest and is probably the result of a short‐term C loss following recent logging at the site. The relationship proposed for soil respiration with soil temperature and soil moisture is useful for understanding and predicting potential changes in Mediterranean forest ecosystems in response to forest management and climate change.     

Diethylstilbestrol-induced perinatal lethality in the rat. I. Relationship to reduced maternal weight gain

An analysis was performed to determine the mechanism of depressed maternal weight gain and its effect on perinatal lethality following prenatal exposure to diethylstilbestrol (DES). Pregnant Sprague-Dawley rats were dosed orally by gavage with DES or corn oil (control) during various intervals of gestation. The maternal weight-gain patterns of control and treated dams and the number of live offspring were recorded. The amounts of feed and water intake and feces and urine output in pregnant dams were measured, and metabolic rate and thyroid hormone levels were also determined. DES (at 45 micrograms/kg/day) was embryo- and fetolethal during implantation and parturition, and there was an accompanying decline in maternal weight. Growth of adult males, nonpregnant females, and weanlings of both sexes was also depressed. During pregnancy, the net intake of feed and water was not altered by the drug, but maternal serum thyroxine and metabolic rate were significantly elevated. Reduced metabolic efficiency, then, is the likely mechanism for weight depression. Reduction of maternal weight gain during pregnancy by DES is a diagnostic indicator of fetolethality, but is probably not causally related to it.     

The wound response in the siphonous algaCaulerpa simpliciuscula C. Ag.: II. The effect of wounding on carbon flow

Summary Following on from a previous study on changes in cytology and fine structure during the wound response in the siphonous green algaCaulerpa simpliciuscula (Dreher, Grant, andWetherbee 1978), changes in the carbon metabolism during this wound response have been studied. There was a decrease in the rate of photosynthesis and an increase in the rate of respiration immediately on wounding, but rates of both photosynthesis and respiration returned to those of unwounded tissues within 6 hours. Wounding depressed the rate of starch synthesis and sucrose synthesis but increased the rate of synthesis of soluble 1,3 ß-glucan, lipid and sulphated polysaccharide. When the flow of carbon from these various compounds was studied by means of pulse chase experiments, it was found that only sucrose and sulphated polysaccharide showed different kinetics in control and wounded tissue. The changes which were observed are consistent with the direct involvement of sulphated polysaccharides in the formation of structures formed during the wound healing process.     

Cell-mediated immunity in human pregnancy: Changes in lymphocyte reactivity during pregnancy and postpartum.

The function of thymus-dependent lymphocytes (T lymphocytes) was studied in women during pregnancy and labor and postpartum by evaluating the blastogenesis of peripheral lymphocytes, which were stimulated with phytohemagglutin-P (PHA-P) in both whole-blood semimicroculture and purifed lymphocyte culture. Data from 353 random samples (203 women) and 50 serial specimens from 10 women revealed that PHA-P induced-lymphocyte blastogenesis was significantly (p less than 0.005) reduced during pregnancy and labor but rapidly returned to normal several days after artificial termination in the early stage of pregnancy as well as after full-term delivery. These results indicate that the T-lymphocyte function in maternal peripheral blood is depressed by causes related to pregnancy. It seems very likely that depressed T-lymphocyte function during pregnancy is caused by inhibitory factors in the blood plasma derived from the feto-placental unit. Questions relating to the inhibitory factors in maternal plasma are discussed.     

The effects of temperature on metabolic rates of different life stages of Calanus glacialis in the Barents Sea

Summary The effects of temperature on rates of respiration, excretion and gut evacuation were examined for copepodite stages and adult female Calanus glacialis collected in areas close to the ice-edge during the arctic summer in the Barents Sea. The various life history stages responded differently to acute temperature changes above the in situ temperature (ca.-1.7°C). Respiration rates of early copepodite stages (C I to C IV) were very variable whereas excretion rates declined with increasing temperature in the range from-1.7°C to +5°C. Rate of oxygen consumption of adult females were independent of temperature between-1.7° and +5°C, but increased as temperature increased from +5° to 10°C. Rates of excretion of copepodite stage V and adult females were independent of temperature in the range from-1.7° to +2°C, whereas excretion of copepodite stages III and IV was negatively related to temperature in the range from-1.7° to +5°C. In C IV, C V and adult females the instantaneous rate of gut evacuation increased with increasing temperature. The different response patterns of metabolic rates of small copepodite stages, copepodite stage V and adult females C. glacialis to acute temperature changes suggest that the capacity for adjustment of ammonia excretion is better developed in C V's and adult females than in the younger life stages.     

Midday depression in root respiration of <Emphasis Type="Italic">Quercus crispula</Emphasis> and <Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis>: its implication for estimating carbon cycling in forest ecosystems

We observed the phenomenon of midday depression in the rate of tree root respiration. Diurnal changes in the root respiration rate of Quercus crispula and Chamaecyparis obtusa were measured under intact conditions using a closed chamber method and a soil respiration measurement system (LI-6400 with a root respiration chamber) in a forest in the foothills of Mt. Fuji. After the measurement of intact root respiration in the field, the root was excised and taken to the laboratory, and the temperature dependence on the respiration rate of the detached root was measured using an open-flow gas exchange system with an infrared gas analyzer (LI-6252). The measurement was conducted in September 2003, August and November 2005, and June 2006. Whereas the root respiration rate of both species under intact conditions increased with increasing soil and root temperatures from dawn to early morning, the respiration rate decreased around midday from 10:00 to 15:00 despite an increment of soil and root temperatures. There was no clear relationship between the intact root respiration rate and root temperature in either species, although the detached root respiration rate of both increased exponentially with the temperature. The amount of the CO₂ efflux estimated using the temperature dependence of detached root respiration tended to underestimate the actual measurement value (intact respiration rate) by 20–50% in both species. These results indicate that evaluating midday depression in root respiration would be important for a more accurate estimation of the carbon cycle or net ecosystem production in forests.